Various biological in vivo screens are utilized for the determination of the antinociceptive activity of potential analgesic agents. Activities are determined subcutaneously and orally, as are acute toxicities for interesting compounds. These tests provide a starting dose for assays in rhesus monkeys for the physical dependence capacity of the drug, by the cooperating units. The goals are the separation of physical dependence from analgesia, the providing of information on the abuse potential of drugs, and the elucidation of the mechanisms determining physical dependence.